1. Field of the Invention
The present invention relates to a circuit for the transmission of data signals between a first subscriber terminal operating with a first data transmission protocol and a second subscriber terminal operating with a second data transmission protocol different from the first data transmission protocol, through a data switching system wherein conversion of the respective data signals from the first subscriber terminal into the data signals compatible to the second subscriber terminals, such that the first subscriber terminal and the second subscriber terminal are connected to separate line adapters of a first or a second group of line adapters.
2. Description of the Prior Art
Circuits of the above described type are known in the prior art, an example of which is German patent DE-PS No. 29 12 649. In this prior art circuit arrangement, a conversion unit, connected to the line adapter of each group of line adapters is provided for the conversion of data signals which are to be transmitted between subscriber terminals having different transmission procedures or protocols. In this conversion unit are input all data signals output from the subscriber terminal operating with a first transmission procedure or protocol. At the same time these data signals are output and sent on to the subscriber terminal with a second transmission protocol differing from that of the first data transmission protocol. Such conversion units are only insertable in data networks over which networks connections between subscriber terminals are established automatically through the use of predetermined switching procedures, ie: in automatic dialing traffic. Internationally however, there still exist data networks with switching facilities designed for non-standard switching procedures. Transition to these types of data networks, through integration with the conversion units known in the prior art, are not possible.
The common carriers operate data networks with standardized transmission procedures, and at present also provide manual switchboards in addition to automatic dialing systems to make transitions to data nets operating with non-standard switching procedures possible. However, until applicants invention, no conversion of data signals has been provided for in such transitions.
In connection with the operation of such manual switchboard positions, a method for the call allocation of calls waiting for released manual switchboard positions is already known in the art, as described in German patent DE-PS No. 25 34 110. In this known method, the waiting calls are entered in a job memory before processing. The individual calls can thereby be allocated different priorities. Upon the release of the manual switchboard positions, the calls are output in the sequence of their input, taking into account the established priorities for processing through the released manual switchboard positions.
The present invention discloses a circuit by means of which data signals may be transmitted between a subscriber terminal operating with a first data transmission protocol and a subscriber terminal operating with a second data transmission protocol which is only attainable by means of a manually switchable connection.